A university student from Florida has made a habit of getting under the skin of some of the world's richest and most powerful people. How? By telling the rest of us where their private planes are - and how much carbon they emit.
Jack Sweeney would like to clarify a few details. For one thing, he thinks Taylor Swift has some good tunes.
However, he believes - despite the threat of legal action - that anybody should be able to see where her private jet is headed, and how often it flies.
"I like to be fair," he told the BBC in an email. "I try to share everyone's info no matter who it is."
But it is specifically information about the locations of private planes of the rich and powerful - posted to his social media accounts - that has repeatedly made the 21-year-old the subject of news stories and legal threats.
On Monday, Mr Sweeney posted a photo of his lawyer's response to Ms Swift's demand that he take down his @TaylorSwiftJets account, which tracks the singer's flights.
The letter, which was dated last month, argued that the jet-tracking account "is engaged in protected speech that does not violate any of Ms. Swift's legal rights".
The photo was captioned with a Swiftian reference: "Look What You Made Me Do".
Mr Sweeney is the son of an airline maintenance operations controller and a teacher, and grew up in the suburbs of Orlando. He says he has always had an interest in aviation and technology, and particularly in Elon Musk's SpaceX and Tesla companies.
Those interests gradually led him to develop a plane tracking website, TheAirTraffic.com, and social media accounts which track the aircraft of celebrities, politicians, tycoons and Russian oligarchs.
The system relies on publicly available data collected by amateur enthusiasts. Aeroplanes in the sky regularly send out information about where they are located, and these signals can be picked up by people using inexpensive receivers on the ground.
This thriving cohort of online plane trackers is part of the larger Osint (open-source intelligence) community, populated by people who delve into masses of freely available online data looking for incriminating, insightful or just plain interesting nuggets of information. It is a motley crew that includes a range of individuals - from the mildly curious to dedicated researchers and committed investigative journalists.
"Originally I was just kind of doing this as a hobby as I found it interesting," said Mr Sweeney, who is currently in his third year of an information technology degree at the University of Central Florida.
As time has gone by, he has found a more defined purpose. He says he believes "in the importance of transparency and public information".
And there is an environmental angle: "The flyers are trying to hide the bad PR of [carbon] emissions."
His data has been used in studies showing the huge carbon footprint of Ms Swift and her entourage, and he criticised the singer in another post on X, sharing a clip of her telling her boyfriend Travis Kelce: "Jet lag is a choice".
"Jet lag is a choice for those who fly in private jets and sleep in queen size beds onboard," he wrote.
The singer says she has bought enough carbon offsets to cancel out emissions from her latest tour twice over.
But there are also privacy issues at stake. Ms Swift contends that revealing the location of her private plane puts her at risk from stalkers.
In a letter first revealed by the Washington Post, lawyers for the singer wrote that plane tracking was a "life-or-death matter" and there was "no legitimate interest in or public need for this information, other than to stalk, harass, and exert dominion and control".
Mr Sweeney rejects those assertions and says there is a fundamental public interest in locating the pop star's plane. His proof? Swifties themselves.
"Her fans, who have grown the TaylorSwiftJets accounts and subreddit, are the ones truly interested," he says. "These tracking accounts consistently have more supporters and fans [than detractors]."
And given world tours and numerous public appearances - including at marquee NFL games - it is usually fairly easy to figure out where Ms Swift will be at some point in the future.
Prior to the Super Bowl, for instance, numerous stories were published speculating about her travel schedule between a gig in Tokyo and the big game in Las Vegas.
Much of this public information is more granular than the location of a plane. Flight data can show who owns an aircraft and where it is in the sky, but not who is on it, or where those people travel to after the plane lands.
But Ms Swift's representatives say the plane information gives exact times and locations of her movements, and notes that one alleged stalker was recently arrested outside her New York home. Her publicist Tree Paine said in a statement: "His posts tell you exactly when and where she would be."
Mr Sweeney also had some advice for the star - gently suggesting that if privacy is her top concern, she could register her private jet through an anonymous corporate entity and perhaps choose an identification code that does not include her birthday and initials.
James Slater, Mr Sweeney's lawyer and the author of the response letter that was posted online this week, says that he does not expect Ms Swift to take any further legal action.
"The letter was an attempt to bully Jack into doing something that legally he doesn't have to do," he said. "Unfortunately folks with power and money often do this.
"He's not doing anything unlawful."
Ms Swift's lawyers did not respond to a request for comment.
One question is whether the Swift fandom will still follow Mr Sweeney's accounts after the latest news.
After the story broke about the legal letter, there was a flurry of online chatter about the case. It included support for Mr Sweeney but also sentiments such as: "Jack Sweeney wants Taylor Swift to die like Princess Diana. I'm not letting this go. I'm so angry."
But it is not the first time Mr Sweeney has been on the receiving end of pressure from the rich and famous.
Most notably, when he purchased Twitter (now X) in 2022, Elon Musk vowed in the name of free speech not to take action against Mr Sweeney's @elonjet tracking account.
In a matter of weeks, however, Mr Musk reversed course, banned the account and threatened to sue, claiming that @elonjet resulted in a stalker tracking him down and climbing on top of his craft when his small child was inside.
Police later identified a member of Mr Musk's security team as a suspect, and said that Mr Sweeney's account had nothing to do with the incident.
Mr Sweeney now runs an account that tracks Mr Musk's jet with a 24-hour delay, in order to comply with a site rule banning real-time location tracking.
He also runs accounts on several social media sites keeping track of planes owned by Kim Kardashian, Jeff Bezos, Bill Gates, Mark Zuckerberg, Donald Trump and others.
But he expressed frustration at the vagaries of social media rules, noting that Meta has suspended the Facebook and Instagram accounts tracking Ms Swift's plane, but has left up various other plane tracking accounts - including the ones which track Mr Zuckerberg's aircraft.
The BBC has contacted Meta for comment.
Meanwhile the planespotters who chat on Mr Sweeney's server on the Discord site have defended his stance - along with their enthusiasm for their hobby. And some admitted they, too, are fans of Ms Swift.
"I have no doubt crazy people have sent her wild threats," said one commenter, "but the airport is not the place where she is vulnerable."
With reporting by Gareth Evans